1. Field of the Invention
The present invention relates generally to surgical device design and fabrication and, more particularly, to a shaft for medical catheters.
2. Background of the Invention
Medical catheters, such as balloon catheters, have been proven efficacious in treating a wide variety of blood vessel disorders. Moreover, these types of catheters have permitted clinicians to treat disorders with minimally invasive procedures that, in the past, would have required complex and perhaps life threatening surgeries. For example, balloon angioplasty is now a common procedure to alleviate stenotic lesions (i.e., clogged arteries) in blood vessels, thereby reducing the need for heart bypass operations.
Previously known catheters are of complex construction, requiring expensive manufacturing steps and construction of great precision to navigate the tortuous pathways of a vessel network. For instance, when a catheter provides inflation fluid to a balloon, a small notch is typically provided in the catheter tube to allow fluid to pass from a lumen within the tube to the balloon. The conventional method for manufacturing this notch is with a laser, which is expensive and often cannot be done in-house. Further, use of a laser creates a heat-affected zone which can lead to fracture of the notch. Moreover, the heat from the laser may cause deformation of the material. This is especially problematic when a straight catheter made of a nickel-titanium alloy is desired. Because the properties of NiTi alloys are extremely temperature sensitive, laser notching may cause buckling or unwanted curvature in the material. Accordingly, there is a need for a notch-forming process which will not cause damage to the material.
Further, profile is often a concern for catheters because of the small space in which the catheters will be inserted. In addition, because catheters must be passed through a tortuous blood vessel network to reach the intended treatment site, it is desirable that the catheters be substantially frictionless to reduce harmful contact with blood vessel walls. Catheters therefore are generally provided with a coating that will increase lubricity of the catheter. These coatings add additional, undesired size to the catheter. Thus, there is a need for a substantially frictionless catheter surface which does not add significant profile to a catheter tube.
In navigating the pathways of a vessel network, a radiopaque marker is often necessary to identify a specified location on the catheter. Such markers are typically placed on the catheter tube near the location of a distal balloon. However, in medical devices employing aspiration catheters and the like, visibility problems often arise with such markers because they are typically made small in order to allow the aspiration catheter to be passed over the marker as it extends towards the distal balloon. Accordingly, there is a need for balloon catheters having markers which can better identify the location of a balloon while inside a blood vessel.